Woodlouse Hunter spider... We have a ton of these in Colorado, mostly found in humid, cool, dark areas like under rocks, dead wood, logs, bricks laying around on the ground... etc. I wouldn't say it's harmless to humans. I've been poking around with these spiders since I was child and from what I've gathered, they are pretty irritable and, though it wont kill a person, the bite is extremely painful... They do hunt Sow bugs, but it's main dish are Woodlouse bugs (hence the name) which are also known as rollie Pollies hence the spider's massive jaws.

Thanks Eric. I seem to have quite a few spiders around but this one is welcome as sow bugs are a bit of a nuisance